A dynamic gas blending system was used to generate controlled vapour concentrations of amphetamine, cocaine, or heroin. An adsorption – thermal desorption – gas chromatographic procedure was developed and used to measure the output vapour concentrations. The vapour pressure of amphetamine at 20 °C was determined, and vapour pressures as a function of temperature have been measured for cocaine and heroin.

Trimethylamine (TMA) concentration in fish tissue is an accepted measure of deterioration. In this preliminary study a direct relation was demonstrated between TMA in the tissue and in the headspace above the fish flesh. A relatively simple but precise procedure was developed for measuring TMA headspace concentration, based on air sampling with Carbotrap or Tenax sorbent tubes and subsequent thermal desorption and gas chromatographic (GC) analysis. Sampling and analysis are completed in less than 5 min. Fish freshness determined by TMA headspacc analysis was consistent with grading estimated by sensory tests, but the instrumental method provided a more objective and quantitative assessment of quality and an estimation of postmortem age of the fish.

AIolecular osygen \\-as subjected to an electrodeless discharge in the pressure range 0.1-3 111111 Mg. The osygen atoll1 concentration was measured as a function of time in a flo\\. system by means of a mo\~able atom cletector which consisted of a platinum wire coatecl with a suitable catnI!.st for atoll1 reco~nbination. The atom concentration was calculated fro111 the heat liberated \\-hen the detector was operated under isother~nal conditions. The surface recombi~la-tion \vas found to be first order in the atom concentration. A value of 7.7X10-5 was obtained for the recornbination coefficient (?) on Pyres. No temperature dependence for y was observecl. The gas phase recombination of osygen atoms \\-as found to be consistent with the ~ncchanism The rate constant for the third-order reaction \\-as found to have a \ -a l~~c of l.OX10" cc2 mole-? scc-I, and a small negative temperature dependence.Evidence \\-as also obtained for the presence of considerable alnoullts of excited a molecular osj.gen in electrically activated 02.

The absolute rate constants for the primary reactions of 0-atoms with ethylene and with butane have been determined in a fast-flow system. The 0-atoms were produced by electrodeless discharge of 0 2 and allowed to react with the hydrocarbon introduced downstream. Addition of a small amount of NO to the gas stream enabled a photometric monitoring of the 0-atoms in the reaction zone. The initial atom concentration was determined by NO2 titration. The reaction could be stopped a t any point in the reaction zone by means of a movable s~~r f a c e of cobalt oxide. The hydrocarbon concentration a t any point coulcl then be determined by condensation downstream and analysis of the proclucts.Rate measurements were carried O L I~ over the te~nperature range -50' to 200' C. T h e rates were found to be consistent with a two-body mechanism. For 0-atoms with ethylene, k = 1.8(&0.6) X10-l1 e-l6O01RT cm3 molecule-' sec-I and for 0-atoms with butane, INTRODUCTIONCvetanoviC has recently measured relative rate constants for the reactions of oxygen atoms with a series of olefins (I). This study enabled him to make interesting deductions about the effect of structure on the rates and mechanisms of these reactions. Absolute rate constants Lvere estimated by comparison with the value for the reaction 0 + NO, reported by Ford and Endow (2), which was, in turn, based on the rate constant for the reaction 0 + O2 + iVI, obtained by Benson and Axworthy (3) from their mechanism for the thermal decomposition of ozone.Kotwithstanding the high caliber of the \\.orl< of these authors, it seemed desirable to measure the absolute value of the rate constant directly for one of these olefin reactions. I t also seemed important to determine its activation energy and steric factor, since such data are virtually non-existent.The present paper reports the measurement of the absolute rate constant and its temperature depeildence for the reaction of 0-atoms with ethylene. For comparison purposes, similar measure~nents mere also obtained for the reaction of 0-atoms with n-butane. Principle of the MethodThe rate constant of interest is that of the initial attack of an 0-atom on an olefin molecule. The subsequent reactions are co~llplicated and lead to a variety of products which depend on the ratio of atomic to molecular oxygen. CvetanoviC has found, however, that the presence of molecular oxygen does not affect the rate of consunlption of the olefin (4), which indicates that the initial 0-atom attack is rate-determining. Consequently, no attempt was made in this worl< a t a detailed product analysis. Can.

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